The present invention relates to construction of three-dimensional objects from multiple layers of sheet material and, in particular, it concerns a method for facilitating the removal of residues from adjacent to such objects.
It is known to build-up three-dimensional structures by attaching together layers of sheet material each cut to the contour of a thin slice of the object. This technique can be used in a wide range of applications, and has particular advantages for rapid construction of small numbers of individual prototypes and models using CAD (computer-aided-design) techniques, or to facilitate the manufacture of three-dimensional objects using CAM (computer-aided-manufacture) techniques. An example of this technique is described in U.S. Pat. No. 3,932,923 to DiMatteo. In most implementations of this technique, the individual layers are first contoured, and then the contoured layers are stacked and bonded together to form the three-dimensional object. This tends to lead to low precision due to registration problems in alignment of the pre-contoured layers.
U.S. Pat. No. 5,071,503 to Berman proposes an alternative approach in which each layer is bonded to the partially-built three-dimensional object by selective application of adhesive and only then is contoured to the required shape. Contouring after bonding of the layer increases the precision by avoiding registration problems. PCT Patent Publication No. WO99/34976 proposes a technique for forming three-dimensional structures of this type employing sheets of polymer materials coated on one side with adhesive, such as are commonly used for laminating applications and the like. Selective adhesion of the layers is achieved by applying a releasing agent to prevent adhesion in regions lying outside the contour of the object to be formed.
While the construction of three-dimensional objects is achieved very effectively by selective adhesion and cutting to shape of sheet material, the removal of the unwanted residues around the object can be problematic. If the residues were to be adhered to each other, large blocks would be formed which, depending upon the shape of the object, would be very difficult or impossible to remove. To avoid such problems, commercial devices based on this technology typically perform selective adhesion so that the layers are attached exclusively within the contours of the object. As a result, the object is typically surrounded and/or filled with very numerous separate sheets of residue material which must then be removed manually. This can be a very laborious and time-consuming job.
An alternative approach is proposed by U.S. Pat. No. 5,637,175 to Feygin et al. in which the residue regions are attached to the adjacent sheets but are cut in a cross-hatched fashion to weaken them. This is said to result in a matrix structure which is attached to the object but relatively weak in strength, so that it can be removed by mechanical means. This clearly adds an additional non-trivial production step.
There is therefore a need for a method for facilitating the removal of residues from adjacent to a three-dimensional object formed from attachment of multiple layers of a sheet material.
The present invention is a method for facilitating the removal of residues from adjacent to a three-dimensional object formed from attachment of multiple layers of a sheet material.
According to the teachings of the present invention there is provided, in a system for constructing a three-dimensional object by selective attachment of a plurality of sheets of flexible material, each sheet being cut along at least one contour line so as to subdivide the sheet into at least one object forming region corresponding to the shape of a layer of the object bounded by a corresponding contour of the object and at least one residue region not required in the constructed object, at least part of each object forming region being attached to object forming regions of adjacent layers, a method for facilitating the removal of the residue regions comprising producing selective attachment of at least part of a plurality of the residue regions to the residue regions of adjacent sheets in such a manner as to form, from at least part of the residue regions of a plurality of the sheets, a plurality of residue elements non-rigidly interconnected such that manual removal of each of the residue elements initiates removal of a subsequent one of the residue elements.
According to a further feature of the present invention, a plurality of the residue regions of at least some of the sheets are selectively cut along at least one separation line.
According to a further feature of the present invention, the separation lines and the selective attachment are configured such that the residue elements circumscribe a residue block such that, after removal of the residue elements, the residue block is readily removable.
According to a further feature of the present invention, each one of at least a first group of the residue elements assumes a generally flat form extending substantially parallel to the sheets.
According to a further feature of the present invention, the selective attachment is configured such that each one of the first group of residue elements is formed from a plurality of the residue regions attached to each other over a major part of their area.
According to a further feature of the present invention, the selective attachment is configured such that the first group of residue elements are interconnected in a generally Z-fold arrangement.
According to a further feature of the present invention, the selective attachment is configured such that adjacent ones of the first group of residue elements are interconnected over no more than a third of their area of overlap.
According to a further feature of the present invention, a plurality of the residue regions of at least some of the sheets are selectively cut along at least one separation line, and one of the first group of residue elements has a maximum dimension L as measured parallel to the sheets, the residue element being subdivided by the separation lines into at least one strip, the strip having a maximum transverse dimension W no more than a third of the maximum dimension L.
According to a further feature of the present invention, the strip follows a generally spiral pattern. According to an alternative feature of the present invention, the strip follows a reciprocating scanning pattern.
According to a further feature of the present invention, a plurality of the residue regions of at least some of the sheets are selectively cut along at least one separation line, and wherein each one of at least a second group of the residue elements assumes a generally flat form extending substantially perpendicular to the sheets.
According to a further feature of the present invention, where at least part of the residue regions are within a side-opening of the object, the method further comprises selectively cutting a plurality of the residue regions of at least some of the sheets along at least one separation line, wherein the separation lines and the selective attachment are configured in such a manner as to form from at least part of the residue regions of a plurality of the sheets adjacent to the side opening a handle attached to a plurality of the residue portions which lie within the side opening, the handle being exposed by removal of other portions of the residue regions adjacent to the side opening so as to be readily accessible for facilitating removal of the residue portions from within the side opening.
There is also provided according to the teachings of the present invention, in a system for constructing a three-dimensional object by selective attachment of a plurality of sheets of flexible material, each sheet being cut along at least one contour line so as to subdivide the sheet into at least one object forming region corresponding to the shape of a layer of the object bounded by a corresponding contour of the object and at least one residue region not required in the constructed object, at least part of each object forming region being attached to object forming regions of adjacent layers, a method for facilitating the removal of the residue regions comprising: (a) selectively cutting a plurality of the residue regions of at least some of the sheets along at least one separation line; and (b) producing selective attachment of at least part of a plurality of the residue regions to the residue regions of adjacent sheets, the separation lines and the selective attachment being configured in such a manner as to form, from at least part of the residue regions of a plurality of the sheets, a plurality of residue elements non-rigidly interconnected such that manual removal of each of the residue elements initiates removal of a subsequent one of the residue elements.
According to a further feature of the present invention, the separation lines and the selective attachment are configured such that the residue elements circumscribe a residue block such that, after removal of the residue elements, the residue block is readily removable.
There is also provided according to the teachings of the present invention, in a system for constructing a three-dimensional object by selective attachment of a plurality of sheets of flexible material, each sheet being cut along at least one contour line so as to subdivide the sheet into at least one object forming region corresponding to the shape of a layer of the object bounded by a corresponding contour of the object and at least one residue region not required in the constructed object, at least part of each object forming region being attached to object forming regions of adjacent layers, a method for facilitating the removal of the residue regions from a side-opening of the object comprising: (a) selectively cutting a plurality of the residue regions of at least some of the sheets along at least one separation line; and (b) producing selective attachment at least part of a plurality of the residue regions to the residue regions of adjacent sheets, the separation lines and the selective attachment being configured in such a manner as to form from at least part of the residue regions of a plurality of the sheets adjacent to the side opening a handle attached to a plurality of the residue portions which lie within the side opening, the handle being exposed by removal of other portions of the residue regions adjacent to the side opening so as to be readily accessible for facilitating removal of the residue portions from within the side opening.